Switching apparatus for magnetic amplifiers



April 18, 1961 J. w. STUART 2,980,847

SWITCHING APPARATUS FOR MAGNETIC AMPLIFIERS Filed Aug. 12, 1957 lg lHllllHlb-E 'gmmullb-s WITNESSES INVENTOR John W; Stuart BY ML 2,980,847 SWITCHING APPARATUS FOR MAGNETIC AMPLIFIERS John W. Stuart, Monroeville, Pa., assignor to Westinghouse fElectric Corporation East Pittsburgh, Pa., a corporation of Pennsylvania 7 Filed Aug. 12, 1957, Ser. No. 677,726

3 Claims. Cl. 323-89 In many applications, it is desirable to have switching apparatus which is operative only upon the'presence or absence of a condition to be detected externally. The detection of a workpiece at a certain location, the detection of the height of a carton on a conveyor, and the detection of card holes for a computer are examples. It is also desirable that the components making up such a switching apparatus have a long life and require very little or no maintenance.

It is an object of this invention vto provide an improved switching apparatus.

It is another object of this invention to provide an improved switching apparatus which conditions its operation upon the detection of the presence or absence of an external condition.

Further objects of this invention will become apparent from the following description when taken in conjunction with the accompanying drawings. In said drawings, for illustrative purposes only, are shown preferred forms of the invention.

Figure 1 is a schematic diagram of. an improved switching apparatus embodying the teachings of this invention;

Fig. 2 is a schematic diagram of a second embodiment of the teachings of this invention; and

Fig. 3 is a schematic diagram of a third embodiment of the teachings of this invention.

In the drawings, the manner in which the windings have been wound on the magnetic core members has been denoted by the polarity dot invention. That is, current flowing into a polarity dot end of a winding will drive an inductively associated core toward positive saturation. Current flowing out of the polarity dot end of a winding will drive an inductively associated core away from positive saturation.

Referring to Fig. 1, there is illustrated an improved switching apparatus which illustrates one embodiment of the teachings of this invention. In general, the apparatus illustrated in Fig. 1 comprises a magnetic amplifier 30 and a radiation sensitive device 11. The magnetic amplifier 30 comprises a magnetic core member 31 constructed of a rectangular-looped core material, a gating circuit 2 for driving the magnetic core member 31 to positive saturation and a reset circuit 3 for driving the magnetic core member 31 to negative saturation.

The gating circuit 2 comprises a gating winding 32 inductively disposed on the saturable magnetic core member 31, a gating rectifier 34, a terminal 42 and a rectifier 41 connected in series circuit relationship between a pair of terminals 18 and 19. The terminal 19 is connected to ground. A non-linear resistance circuit 40 comprising the rectifier 41, the terminal 42 and a resistance 43 is connected in series between ground and a negative source of direct current. An alternating-current voltage is to be c nnected to the terminals 18 and 19.

Patented Apr. 18, 1961 The reset circuit 3 comprises a reset winding 33 induc- {may disposed on the magnetic core member 31, a reset reset circuit 3.

rectifier 35, a terminal 22 and a rectifier 21 connected in series circuit relationship between a pair of terminals 14 and 15. The terminal 14 is grounded. A non-linear I resistance circuit 20 comprising a rectifier 21, the terminal polarities of the two alternating-current voltages are as noted in Fig. 1.

, In operation the gating circuit 2 drives the magnetic core member 31 to substantially positive saturation on a first o1- gating half-cycle of the alternating-current voltage connected to the terminals .18 and 19. Current flow will be from the terminal18 through the gating winding 32,

the rectifier 34 and the rectifier 41 of the non-linear resistance circuit 40 to the terminal 19. On the same half-cycle there will be no flow of current in the reset circuit 3 because of the blocking action of'the rectifier 35.

On the next or reset half-cycle of operation the alternating-current voltage connected to the terminals 14 and 15 will drive the magnetic core member 31 to substantially negative saturation. Current flow will be from the.

terminal 15 through the reset winding 33, the rectifier 35 and the rectifier 21 of the nonlinear resistance circuit 20 to the terminal 14. On this same half-cycle there will be no current flow in the reset circuit 2 because of the blocking action of the rectifier 34. On succeeding half-cycles the magnetic core member 31 will be alternately driven to positive saturation and to negative saturation by the action of the alternating current voltages to be applied to the terminals 18, 1'9 and 14, 15, respectively. Therefore, all the volt-seconds supplied by the alternating current voltage to be connected to the terminals 18 and 19, on the gating half cycle, will be used in driving the magnetic core member 31 to positive saturation and no output will appear across the rectifier 41 of the non-linear resistance circuit 40.

In order for an output to appear from the gating circuit 2, a voltage must be introduced at the terminal 22 of the reset circuit 3 which will block the resetting action of the reset voltage at the rectifier 35. Whenever this voltage is introduced at the terminal 22, there will be no resetting of the flux in the magnetic core member 31 during the reset half-cycle. On the next succeeding gating half-cycle the magnetic core member 31 will remain at substantially positive saturation and an output will appear across the rectifier 41.

The radiation sensitive device 11 will determine whether or not an input voltage applied on the terminal 10 will also be applied to the terminal 22. As is known to those skilled in the art, a radiation sensitive device, such as a photo-transistor, presents a variable impedance in accordance with the amount of radiation received by the radiation sensitive device. When no radiation is applied to the radiation sensitive device 11, the impedance of the device 11 is of a sufiicient magnitude to block the application of the input voltage applied to terminal 10 from the terminal 22 of the reset circuit 3. The application of a radiation input to the radiation sensitive device applied to the terminal 10 to also be applied to the ter minal 22, thereby blocking the reset half-cycle of the magnetic amplifier 30.

esteem 'The non-linear resistance circuits 40 and 20 are wellknown to those skilled in the art and serve the following functions. First, a non-linear resistance circuit presents 'fajl i mreqaar liis i fu f he a e sf s e cnfcui t*3fin'order'to reset the magnetic corefmembercompletely withthe reset voltage when aninput or blocking voltage is absent. Se c':o'ndly, anon-"linear resist ance circuit presents a high" impedance to provide least loading. of a proceeding or driving stage jwhenan input signal ispreseat, The same reasoning applies when using a non-linear resistance circuit in the'gating'circuit 2. It is to be noted jean only be a compromise between the two conflictingre- 'q'uircments noted above. The negative direct current so'u'rc'esmay be pulsating, half-wave sources of'thesarne ffrequen'cy 'as the alternating-current"voltages applied to "the gating circuit 2a'nd' there'set circuit and'properly phased to allow reverse current flow throughthenonlinear resistance circuit rectifiers on thegating and reset half cy'cles.

Summarizing in brief, the apparatus illustrated in Fig.

I has an output from its gating circuit 2 only when there is an input voltage of the proper phase and magnitude present at the terminallt) and a radiation input of sufiicient magnitude'present on the radiation sensitive device 11. If either the radiation or thevoltage input is not present, thenithere will'be no output from the apparatus illustrated in Fig. l. If the input signal to be'applied to applied to the terminal is either an alternating current or pulsating direct current, it must have the proper phase and magnitude to block the reset voltage. However, a pure direct current signal may be used without regard to phasing.

Referring to Fig. 2, there is illustrated another embodimerit of the teachings of this invention, in which like similar to the apparatus illustrated in Fig. 1, only the operation of the reset circuit 4 being different. The gating circuit 2 still functions to drive the magnetic core member 31 to positive saturation on the gating half-cycle of the a1ternating-current voltage to be connected to the terminals 18 and 19. However, the reset circuit 4 functions to'drive the magnetic core member 31 to' substantially negative saturation only when i an input voltage of the proper phase and magnitude is applied to the terminal 10, and then only when the proper radiation input is applied to the radiation sensitive device 11. Ashereinbefore described, the phasing of the input signal at the terminal '10 may be disregarded if the pure direct current input is i used. If the two above conditions are met, then on the reset half-cyle current will flow from the terminal 10 through the radiation sensitive device 11, the isolation rectifier 12, the reset winding 33 and the rectifier 36 to 'the'terminal 22 of the non-linear resistance circuit 20.

Summarizing in brief the operation of the apparatus illustrated in Fig. 2, it is noted that there is an output from the apparatus at all times unless both an input voltage of the proper phase and magnitude is present at the terminal 10. and a radiation input of the proper magni- "tude ispresent to the radiation sensitive device 11. r If either of these two inputs are absent, therevwill be an'output from the gating circuit 2 a'crossthe rectifier 41 of the non-linear resistance'circuit 40.

Referring to Fig. 3, there is illustrated another'crnbodintent of the teachings of this invention, in which like -comthatanimpedance'may'beused in place of anon-linear [resistancecir'cuit butthe proper value ofthis impedance ground.

paratus illustrated in Figs. 2 and 3 is that in Fig. 3 another complete circuit performing the same function as the apparatus illustrated in Fig. 2 has been connected with a circuit identical to that in Fig. 2 to perform a bi-stable function. There has been added an additional magnetic amplifier 80 and an additional radiation sensitive device 61. 'The magnetic amplifier 80 comprises a magnetic core niernber 81, constructed of a rectangular loop core material, a gating circuit 6 for driving the magnetic core 'mei'nb'efSl" to positive saturation and a reset circuit8 for driving the-magnetic core member 81 to negative saturation when a control signal is applied thereto.

The gating circuit 6 comprises a gating winding 82 inductively disposed on the saturable magnetic core member 81, a gating rectifier 84, a terminal 92 and a rectifier 91 connected in series circuit relationship between a pair of terminals 68 and 69. The terminal 69 is connected to Anon-linear resistancecircuit 90 comprising "-the rectifier 91, the terminal 92 and a resistance 93*is connected in series between ground and a negative source of direct current. An alternating-current voltage is to be connected to the terminals'68 and '69.

'4 Thereset circuit 8 comprises a reset winding 83 induc- 1 tively disposed on the core 81 and a reset rectifier 86 con- 'nected' in series circuit relationship betweenan'input isolating rectifier 62 and a terminal 72. -A non-linear resistancecircuit 70 comprising a rectifier 71, the terminal 72 andaresistance 73 is serially connected between ground and anegative source of direct current. The radiation sensitive device 61 is connected between an input terminal 60and the *isolation rectifier 62.

. Theoutputs of the magnetic amplifiers 30 and 80 from the terminals 42 and 92, respectively, have been connected spectively.

The operation of the additional apparatus, the magnetic amplifier 80 and the radiation sensitive device 61, is similar to the operation of the apparatus illustrated in Fig. 2. The distinction in operation is that the alterna- (ting-current voltage to be applied to the terminals 68 and "69 is'of the same frequency as the alternating-current voltage to be appliedto terminals 18 and 19, but is of the opposite'phase as denoted by the polarity markings in Fig. 3.

The operation of the apparatus illustrated in Fig. 3

' may be described as follows. Assume that the magnetic amplifier 30is producing an output. A portion of this output is fed back into the rectifier at 102 to the terminal '101 and resets the magnetic amplifier 80 through the actionof thereset circuit 8. A half-cycle later, therefore, the'magnetic amplifier 80 will produce no output at the terminal 92. There will be then no output fed back from the terminal 92 from the rectifier 104 to the reset circuit 4 of the magnetic amplifier 30. Thus, the

magnetic amplifier 30 on a next half-cycle will again have and the 'cycle'will repeat. This stable output condition is self-sustaining and the output voltage will be a half-Wave voltage inph'ase with the gating voltage applied to the terminals 18 and 19 of the gating circuit 2 of the magnetic amplifier'30.

A voltage applied to the reset circuit 4, of the proper phase and magnitude, will reset the magnetic core member 31 and the magnetic amplifier 30. A half-cycle later "no output will appear at the terminal 42 of the gating circuit 2 of the magnetic amplifier 30. Since there is no output on this half-cycle at the terminal 42, there wfll be noresetting of the magnetic core member 81 of the magnetic amplifier by the impression of a voltage on a reset circuit 8 through the feedback rectifier 102.' The magnetic core member 181 will not be reset and a halfponents of Figs. 2 and 3 have been give'rrthe same refer- 7; cycle later an output will appear at the terminal 92 of ence characters. The main distinction between the apthe gating circuit 6 of the magnetic amplifier 80. This output at the terminal 92 will be substantially 180 out of phase with the previous output which had appeared at the terminal 42. The output from the magnetic amplifier 80 will reset the magnetic core member 31 of the magnetic amplifier 30 by being fed back through the feedback rectifier 104 to the reset circuit 4. The magnetic core member 31 will be reset and on the next half-cycle again no output will appear at the terminal 42. Even though the voltage applied to the reset circuit 4 of the magnetic amplifier 30 is removed, the output will remain at the terminal 92, and thus at the terminal 50 having an opposite phase to the output of the prior stable condition.

The output at the terminal 50 of the apparatus illustrated in Fig. 3 may be shifted back to the original phase by introducing a voltage of the proper phase and magnitude at the terminal 101 of the reset circuit 8 of the magnetic amplifier 80.

The input voltage to be applied to the reset circuits 4 and 8 Will be applied at the input terminals 10 and 60, respectively. As described hereinbefore, the radiation sensitive devices 11 and 61 will continue to regulate the application of the input voltages to the reset circuits 4 and 8 depending upon whether or not they are receiving radiation inputs of the proper value to lower their impedance accordingly.

Summarizing in brief the operation of the apparatus illustrated in Fig. 3, we find that there is an output at the terminal 50 of one phase that may be shifted to the opposite phase by the application of an input voltage of the proper phase and magnitude to the reset circuit of the magnetic amplifier producing the output at the terminal 50. This input voltage, however, will be inefiective to cause a change in the output at the terminal 50 unless the radiation sensitive device associated with the respective input terminal is receiving a radiation input of sufiicient magnitude to lower the impedance of the radiation sensitive device to a relatively low level. I

In conclusion, it is brought out that while the illustrated examples constitute a specific embodiment of my invention, I do not limit myself to the exact details shown, since modification of the same may be varied without departing from the spirit of this invention.

I claim as my invention:

1. In a switching apparatus, in combination, a radiation sensitive device and a magnetic amplifier, said magnetic amplifier comprising a magnetic core member, a gating circuit including a gating winding inductively disposed on said magnetic core member and a gating rectifier, means for applying a first alternating voltage to said gating circuit, said gating circuit being operative so that on one half-cycle of said first alternating voltage substantially all of said voltage is absorbed in driving said magnetic core member from negative to positive saturation and on the other half-cycle of said first alternating voltage said gating rectifier blocks the flow of current through said gating winding, a reset circuit including a reset winding inductively disposed on said magnetic core member and a reset rectifier, said reset circuit being adapted to drive said magnetic core member from positive to negative saturation only upon the application of an input signal to said reset circuit, said radiation sensitive device being connected to said reset circuit to prevent the application of an input signal to said reset circuit except when said radiation sensitive device receives a radiation input.

2. Switching apparatus for initiating a first series of pulses in response to a coincidentally applied first electrical input signal and first radiation input and initiating a second series of pulses substantially out of phase with said first series of pulses in response to a coincidentally applied second electrical input signal and second radiation input comprising a pair of magnetic amplifiers and a radiation sensitive device for each of said magnetic amplifiers, means for connecting an alternating voltage in series with a gating winding of each of said magnetic amplifiers, means responsive to said first electrical input signal for desaturating a magnetic core member of one of said pair of magnetic amplifiers only upon the application of said first radiation input, and means responsive to said second electrical signal for desaturating a magnetic core member of the other of said pair of magnetic amplifiers only upon the application of said second radiation input.

3. Switching apparatus for initiating a first series of pulses in response to a coincidentally applied first electrical input signal and first radiation input and initiating a second series of pulses substantially 180 out of phase with said first series of pulses in response to a coincidentally applied second electrical input signal and second radiation input comprising a pair of magnetic amplifiers and a radiation sensitive device for each of said magnetic amplifiers, means for connecting an alternating voltage in series with a gating winding of each of said magnetic amplifier means, means responsive to said first electrical input signal for desaturating a magnetic core member of one of said pair of magnetic amplifiers only upon the application of said first radiation input, and means responsive to said second electrical signal for desaturating a magnetic core member of the other of said pair of mag netic amplifiers only upon the application of said second radiation input, and means-for feeding back the output of each of said pair of magnetic amplifiers to means for desaturating the other of said pair of magnetic amplifiers.

References Cited in the file of this patent UNITED STATES PATENTS 2,027,311 Fitzgerald Jan. 7, 1936 2,169,093 Edwards Aug. 8, 1939 2,757,297 Evans et al. July 31, 1956 2,770,737 Ramey Nov. 13, 1956 2,798,169 Eckert July 2, 1957 2,820,151 Staegall Ian. 14, 1958 

